Industrial process efficiency method and system

ABSTRACT

This Invention relates to an industrial process efficiency method and system and relates particularly to a method and system for improving the efficiency and performance of any industrial process when loading is at maximum capacity or under maximum capacity. The system incorporates plurality of identical or similar capacity motor-driven pumps to move liquids, slurries, gases and other fluid or fluid-like material at equal reduced speed or at almost equal reduced speed or at similar reduced speed in lieu of the original/traditional designed comparative inefficient pumping arrangements, thereby, to provide the optimum or same flow capacity with respective to the original pumping arrangement&#39;s operating flow capacity. In accordance with the method and system of this invention, significant energy saving can be achieved. Furthermore, the method and system can act responsive to the loading signals or some other reference from which loading can be inferred, thereby a greater extent of energy saving can be accomplished accordingly. The present invention is directed to methods and systems of improving the overall operating performance and efficiency of movement of fluids such as in HVAC systems, paper processing, water and or sewage treatment plants, or any other system that incorporates fluid pumping and the like.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Australian ProvisionalPatent Application No 2006900911 filed on 23 Feb. 2006, the content ofwhich is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This Invention relates to an industrial process efficiency method andsystem and relates particularly to a method and system for improving theefficiency and performance of any industrial process that usesmotor-driven pumps to move liquids, slurries, gases and other fluid orfluid-like material. The invention has particular application in thefield of heating, ventilation and air-conditioning systems (HVAC) used,for example, for comfort conditioning for buildings. More specifically,the present invention is directed to methods and systems of improvingthe overall operating performance and efficiency of movement of fluidssuch as in HVAC systems.

While the invention has broad application throughout all areas ofindustry, such as in cool rooms, paper processing, water and/or sewagetreatment plants, or any other system that incorporates fluid pumpingand the like, for simplicity and ease of understanding the invention, itwill be described herein in relation to its use in HVAC systems. It willbe understood, however, that the invention is not limited to its use insuch systems.

2. Description of Related Art

Compression type HVAC systems and direct expansion air conditioners arethe most commonly used cooling systems for buildings nowadays. HVACsystems and direct expansion air conditioners operate by absorbing heatfrom the space being cooled either directly (direct expansion airconditioners) or by circulating a secondary fluid (e.g. water or air).Rejecting the heat that has been absorbed and has been generated by thecooling apparatus is accomplished almost universally by transferring theheat to the environment outside the building or space.

Known systems typically have a motor which drives a compressor drawinglow pressure refrigerant gas from an evaporator and discharging it as ahigher pressure hot gas into a condenser. In the condenser, the hotgaseous refrigerant is condensed into a high pressure liquid refrigerantwhich flows through an expansion device that regulates the flow ofrefrigerant into the evaporator. The low pressure refrigerant absorbsheat of vaporization from the chilled water or air circulating throughthe evaporator, and low pressure refrigerant vapor is drawn back intothe inlet of the compressor and the cycle is continuously repeated.

Usually such cooling apparatus has some method of regulating coolingcapacity for part load operations, such as a modulating scroll or vaneapparatus which limits the amount of refrigerant through the compressor,or a variable speed apparatus which controls the rotational speed of thecompressor, or both. The chilled water/hot water or chilled air/warmedair is generally circulated through a distribution system for comfortconditioning within the building.

In typical systems, the heat absorbed from the evaporator, along withthe heat added by the compressor, is transferred to the external airthrough the condenser, preferably using cooling towers or the lie.

When water is being chilled by the evaporator to about 4.4 to 10° C., itis then delivered by a chilled water pumps to the cooling load, whichmay include water cooling coils in terminals in which air is cooled anddehumidified.

In the prior art, several arrangements are used for connecting waterchillers into chilled water supply and distribution systems. Further,several arrangements are used for condenser water cooling. However, allsystems proposed previously suffer from inefficiencies when loadingsvary from optimum design loadings.

For example, when cooling loads drop during part-load operation, thewater volume flow rate of the plant loop primary chilled water circuit)keeps in constant flow and maintain in fall capacity which isrecommended by all chiller configuration guidelines due to theirawareness that any reduction of water flow rate in the primary watercircuit may adversely affect the efficiency of chiller and may furtherlead to the instable operation of the chiller. In this connection, allprior arts which attempt to operate the primary chilled water pump atreduced speed in accordance with the load which will lower the waterflow rate of primary chilled water circuit with respect to its originalconstant flow rate arrangement is not recommended by the chiller'smanufacturers.

With regard to the secondary chilled water circuit (also known asbuilding loop), when cooling loads drop during part-load operation, thewater volume flow rate reduces in the building loop because controlvalves have been partially closed. The water pump, therefore, is causedto operate at a loading less than full capacity and therefore at lessthan maximum efficiency. In prior art, someone may use a variable speeddrive to operate the secondary chilled water pump at reduced speed inaccordance with the load, however the water flow rate of the secondarychilled water circuit is lowered too. And the extent of energy saving isnot significant when compared with our present invention.

SUMMARY OF THE INVENTION

It is therefore desirable to provide a method and system to improveperformance and efficiency, and thereby save energy significantly inindustrial systems such as application in cool rooms, paper processing,water and/or sewage treatment plants, or any other system thatincorporates fluid pumping and the like.

It is also desirable to avoid instability in chiller/boiler controls orother industrial process operation, and thus provide for stableoperation of a chiller/boiler in an industrial system such as HVACsystem.

It is also desirable to provide a novel, improved industrial liquidcirculation system control that can operate without encountering controlinstability no matter whether the system demand is at maximum orpart-load.

It is also desirable to incorporate a plurality of pump means inparallel flow relationship to operate at equal reduced speed or almostequal reduced speed or similar reduced speed in lieu of theoriginal/traditional inefficient pumping arrangement, whereby theoperating plurality of pump means providing the optimum or same flowcapacity with respect to a percentage of the flow capacity of theoriginal/traditional pumping arrangement.

It is also desirable to incorporate a plurality of pump means to operateat equal reduced speed or almost equal reduced speed or similar reducedspeed to accomplish a predetermined target (a certain flow rate, acertain pressure differential, a desired chilled water leavingtemperature, a desired discharge pressure, etc.) or in response to aloading signals.

It is also desirable to reduce the wear and tear rate of all componentsof an industrial process including those of industrial liquidcirculation systems to extend the service life of the respectivecomponents which include the chilled water pumps, boiler pumps,condenser water pumps, general purpose pumps and piping of theindustrial liquid circulation system circuit, etc.

It is also desirable to improve the power factor of the system andthereby significantly reduce the demand charge and the associatedutility cost.

In accordance with a first broad aspect of the invention there isprovided an industrial system having one or more liquid circulationcircuits, the system including:

-   -   a plurality of pump means to circulate the liquid through the or        each of said circuits,    -   motor means driving each pump means,    -   load sensing or detecting means to sense operating loads on the        system and the circuits, and    -   speed control means to vary the speed of said motor means to        thereby vary the pumping capacity of each pump means in response        to the detected load on the system.

Preferably, the plurality of pump means each operate at equal reducedspeed or almost equal reduced speed or similar reduced speed inaccordance with the system load, with the motor means driving each pumpmeans, and the speed control means varies the speed of said motor meansthe thereby vary the pumping capacity of each pump means in response tothe detected load on the system or a predetermined target. (I.e. thesame flow capacity with respect to the original/traditional pumpingarrangement.)

In particular embodiments, the pumps may be used in cool rooms forcirculating chilled water, in paper processing systems where the pumpsare used to circulate slurries, cooling water, heating water, and thelike, in water and/or sewage treatment plants, and in a wide range ofother industries where liquids/fluids are pumped for a variety ofpurposes.

In accordance with a second aspect of the invention there is provided arefrigeration system having:

one or more chilled water, condenser water, and boiler water circuits,a plurality of pump means of identical or similar capacity to circulatewater through the or each of said circuits. The plurality of pump meansto be running at equal reduced speed or almost equal reduced speed orsimilar reduced speed, motor means driving each pump means,load detecting means to sense operating load on the system,speed control means to vary the speed of said motor means the therebyvary the pumping capacity of each pump means in response to the detectedload or a predetermined target on the system. (I.e. the same flowcapacity with respect to the original/traditional pumping arrangement.)

In preferred embodiments, the efficiency of the HVAC system's waterdistribution circuit, which includes the chilled water circuit, boilerwater circuit, and condenser water circuit, is improved by controllingtwo or more pumps for each circuit at equal reduced speed or almostequal reduced speed or similar reduced speed in accordance with systemload or a predetermined target.

Preferably, embodiments of the invention employ a plurality of variablespeed drives to operate the associated pumping components. Coolingsystem loading is indicated, i.e. by measuring the present powerconsumption of operating chiller(s)' compressor(s) using a power sensor,or the speed of the operating chiller(s)' compressor(s) using atachometer or measuring the discharged chilled water/boiler temperatureby temperature sensor located in an appropriate location in the watercircuit or some other means from which loading can be inferred orpursuing a predetermined target (i.e. operate at the same flow capacitywith respect to the original pumping arrangement's operating flowcapacity) This strategy sets operation of the plurality of condenserwater pumps, chilled water pumps and boiler pumps running at theirrespective circuit's predetermined equal reduced speed or at almostequal reduced speed or similar reduced speed and can deliver the optimumor same flow capacity with respect to the original/traditional designedpumping arrangements or at a power setting that is a fixed ratio of thecooling system current power ratio or loading (percent of maximum andsubject to limits).

Preferably, the method includes the control and integrating of theplurality of chilled water pumps, boiler water pumps and condenser waterpumps operating simultaneously at respective circuit's predeterminedequal reduced speed or almost equal reduced speed or similar reducedspeed in response to the loading level of the circulating system.

The general formula employed in embodiments of this invention forsetting the power set point for each device may be expressed as:

PR-SP.sub.pd=C*PR.sub.load

Where PR-SP.sub.pd is the power ratio (percent of maximum) set point ofthe respective pumping devices being controlled.

Where PR.sub.load is the current loading/power ratio percent of maximum)that is being utilized by a circuit or system or a HVAC system/airconditioning compressor(s) or apparatus(s).

Where C is a selected constant.

The above equation has a low limit to prevent a power ratio set pointbeing so low as to result in all fluid flow, e.g., all air or waterflow, ceasing, and a high limit to ensure the power ratio set pointwould never rise above undesired flow rates and pressure outputs.

According to a fisher aspect of the invention particularly adapted foruse with HVAC system there is provided a variable capacity, compressiontype, chilled fluid cooling system comprising:

a heat absorbing circuit (also known as chilled water circuit)including:

-   -   two or more chilled water pumps    -   a variable-frequency drive circuit for powering each of the        chilled water pumps;    -   a chiller with evaporator operatively coupled to a numbers of        cooling loads, and a suction line leading back to said chiller;        water passing trough said chiller in a heat exchange        relationship and being cooled; motor means for driving said        chilled water pumps;        means for varying the speed of said motor means;        means for sensing the temperature of water leaving said chiller;        and        means for controlling the variable-speed drive circuit in        response to the present load on the compressor or a        predetermined target so as to regulate operation of the variable        speed pumps and simultaneously running at equal reduced speed or        almost equal reduced speed or similar reduced speed in response        to the load on the compressor or a predetermined target.

Preferably, the chiller includes means for regulating the flow ofrefrigerant gas through the compressor, and the means for determining apresent load on the compressor makes that determination in response to apresent state of the gas flow regulating means in the compressor.

In one form, the means for determining a present load on the compressormakes that determination in response to a level of power applied to thecompressor motor or the sensed temperature of water leaving saidchiller. Alternatively, the means for controlling said means for varyingthe speed of said variable speed pumps simultaneously at equal reducedspeed or at almost equal reduced speed or at similar reduced speed actsresponsive to the manual judgment of skilled personnel.

Preferably, the means for determining a present load on the compressorand the means for controlling the variable speed drive circuit isconfigured to regulate the variable speed drive circuit at thepredetermined percentage of full power thereby running the chilled waterpumps simultaneously at predetermined equal reduced speed or at almostequal reduced speed or at similar reduced speed to save power whilesystem loading is at maximum or below maximum loading.

In one embodiment, the pumps comprise variable speed pumps powered bycorresponding variable-speed drive circuits; and further comprising:

means for controlling the variable speed drive circuit in response tothe present load on the compressor or a predetermined target so as toregulate operation of the chilled water pumps simultaneously at equalreduced speed or at almost equal reduced speed or at similar reducedspeed in response to the load on the compressor or a predeterminedtarget.

In another form, the variable speed drive circuits are connected topower the chilled water pumps, thereby regulating operation of said twoor more pumps simultaneously at equal reduced speed or at almost equalreduced speed or at similar reduced speed responsive to loading on thecompressor or a predetermined target.

According to a Her aspect of the invention there is provided a systemcomprising:

-   -   a heat absorbing circuit (also known as chilled water circuit)        including:    -   three or more chilled water pumps,    -   a variable-speed drive circuit for powering each of the chilled        water pumps;    -   two chillers with evaporators being programmed to one is kept        operating and the other remains shutdown/standby in response to        a certain degree of part load or two are kept operating in        response to a certain degree of full load operatively coupled to        a numbers of cooling loads; and    -   and a suction line leading back to said chillers;        water passing through said chillers in a heat exchange        relationship and being cooled;        motor means for driving said two or more predetermined operating        chilled water pumps;        means for varying the speed of said two or more operating motors        means;        means for sensing the temperature of water leaving said        operating chiller(s);        means for controlling the operating variable-speed drive        circuits in response to the present load on the operating        compressor or a predetermined target so as to regulate operation        of the two or more predetermined chilled water pumps        simultaneously running at equal reduced speed or almost equal        reduced speed or similar reduced speed in response to the load        on the operating compressor or a predetermined target.

Preferably, in accordance with this embodiment, the chillers includemeans for regulating the flow of refrigerant gas through thecompressors, and the means for determining a present loads on thecompressors makes that determination in response to a present state ofthe gas flow regulating means in the compressors.

Preferably, the means for determining a present load on the operatingcompressor(s) makes that determination in response to a level of powerapplied to the operating compressor(s)' motor(s) or in response to thesensed temperature of water leaving said operating chiller.

Preferably, the means for controlling said means for varying the speedof said two or more predetermined operating chilled water pumpssimultaneously at equal reduced speed or at almost equal reduced speedor at similar reduced speed act responsive to the manual judgment ofskilled personnel.

In one arrangement, the means for determining a present load on theoperating compressor and the means for controlling the operatingvariable-speed drive circuit are configured to regulate the operatingvariable-speed drive circuits at the predetermined percentage of fullpower thereby running the two or more operating chilled water pumpssimultaneously at predetermined equal reduced speed or at almost equalreduced speed or at similar reduced speed to save power while systemloading is at maximum or below maximum loading.

According to another aspect of the invention there is provided avariable capacity, compression type, chilled fluid cooling systemcomprising:

a heat rejection circuit (also known as condenser water circuit)including:at least two condenser water pumpsa variable-frequency drive circuit for powering each of the condenserwater pumps;a chiller with condenser operatively coupled to a number of coolingtowersand a suction line leading back to said chiller with condenser;water passing through said chillers with condenser in a heat exchangerelationship and being heated;motor means for driving said two or more operating condenser waterpumps;means for varying the speed of said motors means;means for sensing the temperature of water leaving said chillers; andmeans for controlling the variable-speed drive circuits in response tothe present load on the compressor or a predetermined target so as toregulate operation of the two or more operating condenser water pumpssimultaneously running at equal reduced speed or at almost equal reducedspeed or at similar reduced speed in response to the loading on theoperating compressor(s) or a predetermined target.

In accordance with a still further aspect of the invention there isprovided a method of operating an industrial system having one or morewater, or other liquid circulation circuits, comprising the steps ofproviding a plurality of pump means to circulate water through the oreach of said circuits, operating motor means to drive each pump means,sensing operating loads on the system and the circuits, and vary thespeed of said motor means the thereby vary the pumping capacity of eachpump means in response to the sensed load on the system or apredetermined target.

According to a further aspect of the invention there is provided amethod of operating a variable capacity, compression type cooling systemhaving a plurality of chilled water pumps, condenser water pumps, boilerpumps, the method comprising the steps of determining a present loadlevel of the compressor or a pursuing a predetermined target andregulating operation of the respective plurality of primary chilledwater pumps, secondary chilled water pumps, boiler pumps, condenserwater pumps running at respective circuit's predetermined equal reducedspeed or at almost equal reduced speed in response to the present loadlevel of the compressor(s) or pursuing a predetermined target.

According to another aspect of the invention there is provided anindustrial fluid circulating system having one or more fluid circulationcircuits, the system including:

-   -   a plurality of pump means to circulate the fluid through the or        each of said circuits,    -   motor means driving each pump means,    -   load sensing or detecting means to sense operating loads on the        system and the circuits, and    -   speed control means to vary the speed of said motor means to        thereby vary the pumping capacity of each pump means in response        to the detected load on the system.

According to a further aspect of the invention there is provided amethod of operating an industrial system having one or more water, orother fluid circulation circuits comprising the steps of:

providing a plurality of pump means to circulate fluid through the oreach of said circuits;operating motor means to drive each pumps means,sensing operating loads on the system and the circuits; andvarying the speed of said motor means at respective circuit'spredetermined equal reduced speed or at almost equal reduced speed or atsimilar reduced speed to thereby vary the pumping capacity of each pumpmeans in response to the sensed load on the system; or in response to apredetermined target; or in response to manual judgment of skilledpersonnel.

According to a still further aspect of the invention there is providedan industrial fluid circulating system having a plurality of fluidcirculation circuits, the system including:

-   -   a variable capacity, compression type, chilled fluid cooling        system comprising:        a single circuit chilled water system including:    -   at least two chilled water pumps;    -   a chiller with evaporator operatively coupled to a numbers of        cooling loads        and a suction line leading back to said chiller;    -   water passing through said chiller in a heat exchange        relationship and being cooled;    -   motor means for driving said chilled water pumps;    -   a variable-speed drive circuit for powering each of the motor        means to vary the speed of the chilled water pumps;    -   means for sensing the temperature of water leaving said chiller;        and    -   means for controlling the variable-speed drive circuit in        response to the present load on a system compressor so as to        regulate operation of the said at least two chilled water pumps        running at equal reduced speed or at almost equal reduced speed        or at similar reduced speed simultaneously in response to the        load on the compressor.

In order that the invention is more readily understood, embodimentsthereof will now be described with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a typical prior art HVAC system with awater-cooled condenser

FIG. 2 is a schematic of a typical prior art HVAC system with aplant-through building loop (also known as “single circuit”)chilled/boiler water system.

FIG. 3 is a schematic of a typical prior art HVAC system with aplant-building loop (also known as “primary-secondary water circuit”)chilled/boiler water system.

FIG. 4 is a schematic of a typical prior art HVAC system with acondenser water circuit

FIG. 5A is a schematic of a typical HVAC system with a plant-throughbuilding loop (also known as “single circuit”) chilled/boiler watersystem in accordance with one embodiment of the invention,

FIG. 6A is a schematic of a typical HVAC system with a plant-throughbuilding loop (also known as “single circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 7A is a schematic of a typical HVAC system with a plant-buildingloop (also known as “primary-secondary circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 8A is a schematic of a typical HVAC system with a plant-buildingloop (also known as “primary-secondary circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 9A is a schematic of a typical HVAC system with a plant-buildingloop (also known as “primary-secondary circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 10A is a schematic of a typical HVAC system with a plant-buildingloop (also known as “primary-secondary circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 11A is a schematic of a typical HVAC system with a plant-buildingloop (also known as “primary-secondary circuit”) chilled/boiler watersystem in accordance with another embodiment of the invention,

FIG. 12A is a schematic of a typical HVAC system with a condenser watercircuit in accordance with another embodiment of the invention,

FIG. 13A is a schematic of a typical HVAC system with a condenser watercircuit in accordance with another embodiment of the invention, and

FIG. 14A is a schematic of a typical HVAC system with a condenser watercircuit in accordance with another embodiment of the invention,

PRIOR ART

FIG. 1 illustrates the major components of a typical compression cyclecooling apparatus. In this system, a motor (101) drives the compressor(102), which draws low pressure refrigerant gas from the evaporator(103) through a suction line (104), compresses it, and discharges it asa higher pressure hot gas through a hot gas line (105) into thecondenser (106). In the condenser, the hot gaseous refrigerant iscondensed into a liquid by rejecting heat to outside air by blowingoutside air across the condenser with a fan driven by an electric motor(118) (not shown here) or by rejecting heat to tepid water from acooling tower (107) through a condenser water circuit (116) whichemploys condenser water pump(s) (117). The condensed liquid refrigerantflows through an expansion device (109) that regulates the flow ofrefrigerant into the evaporator (103), which is held at a low pressureby the operation of the compressor. The low pressure environment causesthe refrigerant to change state to a gas and as it does so, it absorbsthe required heat of vaporization from the chilled water or aircirculating through the evaporator, entering at (110) and leaving at(111). The low pressure refrigerant vapor is drawn into the inlet of thecompressor and the cycle is continuously repeated. Usually such coolingapparatus has some method of regulating cooling capacity for part loadoperations such as a modulating scroll or vane apparatus (112) whichlimits the amount of refrigerant through the compression device, or avariable speed apparatus (113) which controls the rotational speed ofthe compression device, or both. The chilled water/hot water or chilledair/warmed air is circulated through a distribution system (115) forcomfort conditioning, or to provide cooling for certain processes withinthe building. In this circuit (115), the heat absorbed from theevaporator (103) along with the heat added by the compressor (102) arerejected to the outside air through condenser fan(s) (not shown here) orcooling tower(s) (107).

The chilled water being cooled by the evaporator (103) (about 4.4 to10□) is then delivered by the chilled water pump(s) (114) to the coolingload(s) (108) which include: water cooling coils in AHUs and terminalsin which air is cooled and dehumidified. After flowing through thecooling load(s) (108), the chilled water increases in temperature up to(about 15.6 to 18.3□) and then returns to the evaporator (103).

In the prior art, there are several arrangements for connecting waterchillers into chilled water supply and distribution systems. FIG. 2illustrates a typical plant-through building loop system (200) (alsoknown as “single circuit system”). The plant-through building loopsystem include: chilled water, hot water or dual-temperature watersystems in which water is transported only by plant (chiller/boiler)pump(s). A plant-through-building loop water system using bypassthrottling flow is one of the older chilled/hot water systems that havebeen adopted in commercial buildings since the use of two-way controlvalves. For each chiller/boiler (201), a corresponding plantconstant-speed water pump (202) is installed. The chilled or hot wateris supplied to the coils and terminals (204,205 and 206) through thesupply (207) and return (208) mains and branches, and is then returnedto the chiller/boiler (201). There is a crossover bridge (209, sometimescalled a common pipe) that connects the supply and return mains atjunctions (210) and (211). A bypass two-way control valve (212) is ofteninstalled on the crossover bridge. A pressure-differential transmitter(213) and pressure relief valve are used to maintain a set pressuredifferential across the supply and return mains by modulating theopening of the bypass two-way control valve (212) when the systempressure tends to increase during part-load operation. A portion of thewater is throttled in the control valve and flows through the bypasscrossover (209). It is then combined with water from the return main(208) and returns to the chiller/boiler (201). A constant flow (orapproximately constant flow) is maintained in the chiller/boiler (201).

A plant-through-building loop using bypass throttling control cannotsave much pumping energy during part-load operation; it sometimesconsumes even more energy. The surplus energy which is more thanrequired is dissipated by mechanical means. Plant-through-building loopusing bypass throttling control still has applications in small projectsand especially in retrofit where space may not be available for aplant-building loop system.

FIG. 3 illustrates another prior art chiller arrangement: Plant-buildingloop (300) water systems. This is also called Primary-Secondary loop (orcircuit) water systems, and is the widely adopted water systems forlarge commercial HVAC installations in the world today. A plant-buildingloop (300) include: chilled water, hot water, or dual-temperature watersystem consists of two piping loops, namely, plant loop primary loop)(301) and building loop (secondary loop) (302).

In plant loop (primary loop) (301), there are chillers (303,304), plantpumps (primary chilled water pumps) (305, 306,), diaphragm expansiontank, corresponding pipes and fittings, and control systems. A constantvolume flow rate is maintained in the evaporator of each chiller(303,304). The chilled water volume flow rate in the plant loop (301)will vary when a chiller (303 or 304) and its associated chiller pump(305, 306,) are turned on or off.

In building loop (secondary loop) (302) there are cooling loads(312,313), building pumps (secondary chilled water pumps) (314), two-waycontrol valves (325,326) and control systems, and corresponding pipes,fittings, and accessories.

The water flow in the building loop (302) is varied as the coil load ischanged from the design load to part-load.

A short common pipe (321), sometimes also called a bypass, connectsthese two loops (301 and 302) and combines them into a plant-buildingloop (300). The common pipe (321) ensures that differences in flowsbetween the primary and secondary water circuits will not affect theoperation of either circuit. The common pipe (321) serves as a bypassfor both circuits, which is needed to maintain constant flow in theprimary circuit.

At design load, chilled water leaving the chillers (303,304) at point(322) flows through the junction of the common pipe (321), plant loop(301), and building loop (302) at point (323), is extracted by thebuilding pump (secondary chilled water pump) (314), and is supplied tothe cooling loads (312,313). From the cooling loads (312,313), chilledwater returns through another junction of the building loop (302) atpoint (324). There is only a very small amount of bypass chilled waterin the common pipe that flows in the direction from point (323) to(324). The chilled water returned from the cooling loads (312,313) isthen combined with the bypass water from the common pipe (321) andbypass line (330) and is extracted by the plant pump(s) (305,306) andenters the chiller(s) (303,304) for cooling again.

When the cooling loads (312,313) drop during part-load operation, thewater volume flow rate reduces in the building loop (302) because thecontrol valves (325,326) have been partially closed. Chilled water thendivides into two flows at the junction (328). One is supplied to thecooling loads (312,313); the remaining water bypasses the building loopby flowing through the bypass line (330) through valve (327) which iscontrolled by a differential pressure sensor (329), is extracted by theplant pump(s) (305,306) and returns to the chiller(s) (303,304).

FIG. 4 illustrates a prior art condenser water circuit (400) of HVACsystem. In this condenser water circuit (400), the heat generated byvarious cooling apparatus, i.e. compressor (404) and cooling load(s)(406) are absorbed by condenser water at point (407), the condenserwater is then forced through the cooling tower (402) by condenser waterpump (409), and then back to condenser (401) at point (408) again. Inthis condenser (401), tepid water from the sump of a cooling tower (402)is circulated through the condenser (401) by a pump (409), and then tospray nozzles or distribution flume which distributes the water overslats or plastic fill that breaks the water up into droplets with a verylarge surface area such that a fan driven by an electric motor forcesair over the water, evaporating a portion of it to provide adiabaticcooling of the water. The cooled water gathers in the sump where thewater lost through evaporation is made up by adding water from a watersupply. The level of water in the tower sump is maintained by a waterlevel sensor, which operates a valve. Water in the sump is drawn throughthe condenser (401) to provide continuous rejection of the heat absorbedfrom the cooling loads through the evaporator (403) and that generatedby the cooling apparatus, such as the compressor (404).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 5A illustrates one embodiment of this invention utilizing variablespeed control of two chilled water pumps/boiler pumps operating atpredetermined equal reduced speed or at almost equal reduced speed or atsimilar reduced speed in lieu of the original/traditional pumpingarrangement as shown in FIG. 2. A chilled water/boiler circuit (500A)(plant-through building loop system, also known as “single circuitsystem”), in this case, two (chilled water/boiler) pumps (502A and 503A)of identical or similar capacity are deployed to transport the producedchilled water/hot water throughout the water circuit (500A). Said twopumps (502A and 503A) are connected in parallel and operate inpredetermined equal reduced speed or almost equal reduced speed orsimilar reduced speed simultaneously. Said two pumps (502A and 503A) andrespective motors are controlled by two variable speed drives (512A and513A) and the two drives are commanded by a Controller (514A). TheController (514A), monitors the present loading on the water system(500A) either by measuring the present power consumption of operatingchiller's compressor using a power sensor, or the speed of the operatingchiller's (501A) compressor using a tachometer or measuring dischargedchilled water/boiler temperature by temperature sensor located inappropriate location in the water circuit or some other means from whichloading can be inferred. Based on that loading signal (515A), analgorithm calculates the optimum power loading (subject to limits) forthe pumps and sends an output signal (516A) to the variable speed drives(512A and 513A) operating the (chilled water/boiler water) pumps andcorresponding motors (502A and 503A) such that the pumps' motors (502Aand 503A) were incorporated to run at equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously and operateat the optimum power percentage (or ratio) of maximum power draw basedon the present percentage (or ratio) of maximum loading on the watercircuit (500A).

In the event of VSD (512A or 513A) or chilled water pumps/boiler pumps(502A or 503A) and corresponding motors's failure, an integral bypassswitch (not shown here as it is irrelevant to the present invention),can be operated either manually or automatically to allow the operativemotor to be operated at full speed. At the same time, an alarm signalwill be shown and sent to an appropriate location as required alertingappropriate personnel to take necessary actions.

FIG. 6A illustrates second embodiment of this invention utilizingvariable speed control of three chilled water pumps/boiler pumpsoperating at predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed in lieu of the original/traditionaldesigns' pumping arrangement as shown in FIG. 2. A chilled water/boilercircuit (600A) (“plant-through building loop system”, also know as“single circuit system”), in this case, three (chilled water/boiler)pumps (602A, 603A, 617A) of identical or similar capacity are deployedto transport the produced chilled water/hot water throughout the watercircuit (600A). Said three pumps (602A, 603A, and 617A) are connected inparallel and operate in predetermined equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously. Said threepumps (602A, 603A, 617A) and respective motors are controlled by threevariable speed drives (612A, 613A, 618A) and the three drives arecommanded by a Controller (614A). The Controller (614A), monitors thepresent loading on the water system (600A) either by measuring thepresent power consumption of operating chiller's compressor using apower sensor, or the speed of the operating chiller's (601A) compressorusing a tachometer or measuring discharged chilled water/boilertemperature by temperature sensor located in appropriate location in thewater circuit or some other means from which loading can be inferred.Based on that loading signal (615A), an algorithm calculates the optimumpower loading (subject to limits) for the pumps and sends an outputsignal (616A) to the variable speed drives (612A, 613A, 618A) operatingthe (chilled water/boiler water) pumps and corresponding motors (602A,603A, 617A) such that the pumps' motors (602A, 603A, 617A) wereincorporated to run at equal reduced speed or almost equal reduced speedor similar reduced speed simultaneously and operate at the optimum powerpercentage (or ratio) of maximum power draw based on the presentpercentage (or ratio) of maximum loading on the water circuit (600A).

In the event of VSD (612A, 613A, 618A) or chilled water pumps/boilerpumps (602A, 603A, 617A) and corresponding motors's failure, an integralbypass switch (not shown), can be operated either manually orautomatically to allow the operative motor to be operated atpredetermined speed. At the same time, an alarm signal will be shown andsent to an appropriate location as required alerting appropriatepersonnel to take necessary actions.

FIG. 7A illustrates third embodiment of this invention utilizingvariable speed control of two primary chilled water/boiler pumpsoperating at predetermined equal reduced speed or almost reduced speedor similar reduced speed in lieu of the original/traditional pumpingarrangement as shown in FIG. 3 when one chiller is operating. A chilledwater/boiler circuit (700A) (“plant-building loop system” also known as“primary-secondary chilled/boiler water circuit”), in this case, in theplant loop (701A), two plant pumps; in the combination of (705A and706A) or (705A and 707A) or (706A and 707A) of identical or similarcapacity are deployed to transport the produced chilled/boiler waterthrough the plant loop water circuit (701A) (also known as “primaryloop”) if only one chiller/boiler (703A or 704A) is operating at themean time and the other remains on standby in accordance with thecurrent loading. The respective two predetermined pumps (thepredetermined combination of 705A, 706A, and 707A) are connected inparallel and operate in predetermined equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously. The pumpsand the corresponding driving motors are controlled by correspondingvariable speed drive (VSD) (730A corresponds to plant pump 705A, 731Acorresponds to plant pump 706A, 732A corresponds to plant pump 707A) andthe said drives (730A, 731A, 732A) are commanded by a Controller (733A).The Controller (733A), monitors the present loading on the water systemeither by measuring the present power consumption of operating chiller's(703A or 704A) compressor using a power sensor, or the speed of theoperating chiller's (703A or 704A) compressor using a tachometer ormeasuring discharged chilled/boiler water temperature by temperaturesensor located in appropriate location in the water circuit or someother means from which loading can be inferred. Based on that loadingsignal (734A), an algorithm calculates the optimum power loading(subject to limits) for the pumps and sends an output signal (735A) tothe respective two predetermined variable speed drives (730A,731A,732A)operating the two corresponding plant pumps (said combination of705A,706A,707A) such that the two corresponding pumps (said combinationof 705A,706A,707A) were incorporated to run at equal reduced speed oralmost equal reduced speed or similar reduced speed simultaneously andoperate at the optimum power percentage (or ratio) (subject to limits)of maximum power draw based on the present percentage (or ratio) ofmaximum loading (subject to limits) on the water circuit (700A).

As above, in the event of variable speed drive(s) or plant pump(s)failure, an integral bypass switch (736A, not shown here), can beoperated either manually or automatic, will allow said pumps to beoperated at fall speed. At the same time, an alarm signal will be shownand sent to an appropriate location as required alerting appropriatepersonnel to take necessary actions.

FIG. 8A illustrates a fourth embodiment of this invention utilizingvariable speed control of three primary chilled water/boiler pumpsoperating at predetermined equal reduced speed or at almost equalreduced speed or at similar reduced speed in lieu of theoriginal/traditional designed pumping arrangement as shown in FIG. 3when one chiller (803A or 804A) is operating. A chilled water/boilercircuit (800A) (plant-building loop system) (also known asprimary-secondary chilled/boiler water circuit), In this case, in theplant loop (801A), three plant pumps (805A, 806A and 807A) of the sameor near the same capacity are deployed to transport the producedchilled/boiler water through the plant loop water circuit (801A)(primary loop) if one chillers/boilers (803A or 804A) is operating atthe mean time in accordance with the current loading.

The three pumps (805A, 806A and 807A) are connected in parallel andoperate in predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed simultaneously in lieu of theoriginal/traditional designed pumping arrangement as shown in FIG. 3.The three pumps (805A, 806A and 807A) and corresponding motors arecontrolled by respective variable speed drives (VSD830A corresponds toplant pump 805A, VSD831A corresponds to plant pump 806A, VSD 832Acorresponds to plant pump 807A) and the said drives (830A, 831A, 832A)were commanded by a Controller (833A). The Controller (833A), monitorsthe present loading on the water system either by measuring the presentpower consumption of operating chiller' (803A or 804A) compressor usinga power sensor, or the speed of the operating chiller' (803A or 804A)compressor using a tachometer or measuring the discharged chilledwater/boiler temperature by temperature sensor located in appropriatelocation in the water circuit or some other means from which loading canbe inferred. Based on that loading signal (834A), an algorithmcalculates the optimum power loading (subject to limits) for the pumpsand sends an output signal (835A) to the three variable speed drives(830A, 831A, 832A) operating the three corresponding plant pumps (805A,806A, 807A) such that the three plant pumps (805A, 806A and 807A) wereincorporated to run at equal reduced speed or at almost equal reducedspeed or at similar reduced speed simultaneously and operate at theoptimum power percentage (or ratio) (subject to limits) of maximum powerdraw based on the present percentage (or ratio) of maximum loading onthe water circuit (800A).

In the event of variable speed drive(s) or plant pump(s) failure, anintegral bypass switch (836A, not shown here), can be operated eithermanually or automatic, will allow said operative pumps to be operated ata predetermined speed. At the same time, an alarm signal will be shownand sent to appropriate location as required alerting appropriatepersonnel to take necessary actions.

FIG. 9A illustrates a fifth embodiment of this invention utilizingvariable speed control of three primary chilled water/boiler pumpsoperating at predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed simultaneously in lieu of theoriginal/traditional designed pumping arrangement as shown in FIG. 3when two chillers (903A and 904A) are operating. A chilled water/boilercircuit (900A) (“plant-building loop system” also known as“primary-secondary chilled/boiler water circuit”), In this case, in theplant loop (901A), three plant pumps (905A, 906A and 907A) of the sameor near the same capacity are deployed to transport the producedchilled/boiler water through the plant loop water circuit (901A) (alsoknown as “primary loop”) if two chillers/boilers (903A and 904A) areoperating at the mean time in accordance with the current loading.

The three pumps (905A, 906A and 907A) are connected in parallel andoperate in predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed simultaneously. The three pumps (905A,906A and 907A) and corresponding motors are controlled by respectivevariable speed drives (VSD930A corresponds to plant pump 905A, VSD931Acorresponds to plant pump 906A, VSD 932A corresponds to plant pump 907A)and the said drives (930A, 931A, 932A) were commanded by a Controller(933A). The Controller (933A), monitors the present loading on the watersystem either by measuring the present power consumption of operatingchillers' (903A and 904A) compressor using a power sensor, or the speedof the operating chillers' (903A or 904A) compressor using a tachometeror measuring the discharged chilled water/boiler temperature bytemperature sensor located in appropriate location in the water circuitor some other means, from which loading can be inferred. Based on thatloading signal (934A), an algorithm calculates the optimum power loading(subject to limits) for the pumps and sends an output signal (935A) tothe three variable speed drives (930A, 931A, 932A) operating the threecorresponding plant pumps (905A, 906A, 907A) such that the three plantpumps (905A, 906A and 907A) were incorporated to run at equal reducedspeed or almost equal reduced speed or similar reduced speedsimultaneously and operate at the optimum power percentage (or ratio)(subject to limits) of maximum power draw based on the presentpercentage (or ratio) of maximum loading on the water circuit (900A).

In the event of variable speed drive(s) or plant pump(s) failure, anintegral bypass switch (936C, not shown here), can be operated eithermanually or automatic, will allow said operative pumps to be operated ata predetermined speed. At the same time, an alarm signal will be shownand sent to appropriate location as required alerting appropriatepersonnel to take necessary actions.

FIG. 10A illustrates sixth embodiment of this invention utilizingvariable speed control of four primary chilled water/boiler pumpsoperating at predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed in lieu of the original/traditionalpumping arrangement as shown in FIG. 3 when two chillers are operating.A chilled water/boiler circuit (1000A) (“plant-building loop system”also known as “primary-secondary chilled water/boiler circuit”), In thiscase, in the plant loop (1001A), four plant pumps(1005A,1006A,1007A,1037A) of the same or near the same capacity aredeployed to transport the produced chilled/boiler water through theplant loop water circuit (1001A) (primary loop), two chillers/boiler(1003A and 1004A) are operating at the mean time in accordance with thecurrent loading.

The four plant pumps (1005A, 1006A, 1007A, and 1037A) are connected inparallel and operate in predetermined equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously. Said fourpumps (1005A,1006A,1007A,1037A) and corresponding motors were controlledby respective variable speed drives (VSD1030A corresponds to plant pump1005A, VSD1031A corresponds to plant pump 1006A, VSD1032A corresponds toplant pump 1007A, VSD1036A corresponds to plant pump 1037A) and the saiddrives (1030A,1031A,1032A,1036A) were commanded by a Controller (1033A).The Controller (1033A), monitors the present loading on the water systemeither by measuring the present power consumption of operating chillers'(1003A and 1004A) compressors using a power sensor, or the speed of theoperating chillers' (1003A and 1004A) compressors using a tachometer ormeasuring discharged chilled/boiler water temperature by temperaturesensor located in appropriate location in the water circuit or someother means from which loading can be inferred. Based on that loadingsignal (1034A), an algorithm calculates the optimum power loading(subject to limits) for the pumps and sends an output signal (1035A) tothe respective variable speed drives (1030A,1031A,1032A,1036A) operatingthe corresponding plant pumps (1005A,1006A,1007A,1037A) such that thefour pumps (1005A,1006A,1007A,1037A) were incorporated to run at equalreduced speed or almost equal reduced speed or similar reduced speedsimultaneously and operate at the optimum power percentage (or ratio)(subject to limits) of maximum power draw based on the presentpercentage (or ratio) of maximum loading on the water circuit (1000A).

In the event of variable speed drive(s) or plant pump(s) failure, anintegral bypass switch (1036A, not shown here), can be operated eithermanually or automatic, will allow said operative pumps to be operated ata predetermined speed. At the same time, an alarm signal will be shownand sent to an appropriate location as required alerting appropriatepersonnel to take necessary actions.

FIG. 11A illustrates seventh embodiment of this invention utilizingvariable speed control of two secondary chilled water/boiler pumpsoperating at predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed in lieu of the original/traditionaldesigned pumping arrangement as shown in FIG. 3 when chiller(s) isoperating. A chilled/boiler water circuit (1100A) (“plant-building loopsystem” also known as “primary-secondary chilled/boiler water circuit”),In this case, in the plant loop (1101A) (also known as primary loop),chilled/boiler water leaving the chillers/boilers (1103A, 1104A) atpoint (1122A) flows through the junction of the common pipe (1121A),plant loop (1101A), and building loop (1102A) at point (1123A), isextracted by the building pumps (also called secondary chilled/boilerwater pumps) (1114A and 1115A); and is supplied to the cooling loads(1112A, 1113A). Two building pumps (secondary chilled/boiler waterpumps) (1114A and 1115A) of the same or near the same capacity aredeployed to transport the produced chilled/boiler water trough thebuilding loop water circuit (1102A) (also known as “secondary loop”)

The pumps (1114A and 1115A) are connected in parallel and operate inpredetermined equal reduced speed or almost equal reduced speed orsimilar reduced speed simultaneously. The pumps (1114A and 1115A) andcorresponding motors were controlled by corresponding variable speeddrive (VSD1130A corresponds to building pump 1114A, VSD1131A correspondsto building pump 1115A) and the said drives (1130A and 1131A) werecommanded by a Controller (1133A). The Controller (1133A), monitors thepresent loading on the water system either by measuring the presentpower consumption of operating chiller(s)' (1103A, 1104A) compressorusing a power sensor or the speed of the operating chiller(s)' (1103A or1104A) compressor using a tachometer and measuring dischargedchilled/boiler water temperature by temperature sensor located inappropriate location in the water circuit and the pressure differentialof the building loop by pressure differential transmitter located inappropriate location in the building loop, or some other means fromwhich loading can be inferred. Based on these loading signals (1134A),an algorithm calculates the optimum power loading (subject to limits)for the building pumps (1114A and 1115A) and sends an output signal(1135A) to the respective two variable speed drives (1130A and 1131A)operating the two corresponding building pumps (1114A and 1115A) suchthat the two corresponding building pumps (1114A and 1115A) wereincorporated to run at equal reduced speed or almost equal reduced speedor similar reduced speed simultaneously and operate at the optimum powerpercentage (or ratio) (subject to limits) of maximum power draw based onthe present percentage (or ratio) of maximum loading (subject to limits)on the building loop circuit (1102A).

As described above, in the event of variable speed drive(s) or buildingpump(s) failure, an integral bypass switch (1136A, not shown here), canbe operated either manually or automatic, will allow said operative pumpto be operated at full speed. At the same time, an alarm signal will beshown and sent to an appropriate location as required alertingappropriate personnel to take necessary actions.

FIG. 12A illustrates eighth embodiment of this invention utilizingvariable speed control of two condenser water pumps operating atpredetermined equal reduced speed or almost equal reduced speed orsimilar reduced speed in lieu of the original/traditional designs'pumping arrangement as shown in FIG. 4 when one chiller is operating. Acondenser water circuit (1200A), In this case, in the condenser watercircuit (1200A), two condenser pumps (1206A and 1207A) of the same ornear the same capacity are deployed to transport the produced condenserwater generated by the chiller (1203A) through the condenser watercircuit (1200A) and reject the heat energy through the cooling tower(1202A) to outside atmosphere.

The condenser pumps (1206A and 1207A) are connected in parallel andoperate in predetermined equal reduced speed or almost equal reducedspeed or similar reduced speed simultaneously. The condenser pumps(1206A and 1207A)) and corresponding motors are controlled bycorresponding variable speed drive (VSD1230A corresponds to condenserpump 1206A, VSD1231A corresponds to condenser pump 1207A) and the saiddrives (1230A, 1231A) are commanded by a Controller (1233A). TheController (1233A), monitors the present loading on the water systemeither by measuring the present power consumption of operating chiller's(1203A) compressor using a power sensor, or the speed of the operatingchiller's (1203A) compressor using a tachometer or measuring dischargedchilled water temperature and the discharged condenser water temperatureby temperature sensor located in appropriate location in the watercircuit or some other means from which loading can be inferred. Based onthese loading signals (1234A), an algorithm calculates the optimum powerloading (subject to limits) for the pumps and sends an output signal(1235A) to the respective two variable speed drives (1230A,1231A)operating the two corresponding condenser pumps (1206A,1207A) such thatthe two corresponding condenser pumps (1206A,1207A) were incorporated torun at equal reduced speed or almost equal reduced speed or similarreduced speed simultaneously and operate at the optimum power percentage(or ratio) (subject to limits) of maximum power draw based on thepresent percentage (or ratio) of maximum loading (subject to limits) onthe condenser water circuit (1200A).

As described above, in the event of variable speed drive(s) or condenserwater pump(s) failure, an integral bypass switch (1236A, not shownhere), can be operated either manually or automatic, will allow theoperative pump to be operated at full speed. At the same time, an alarmsignal will be shown and sent to an appropriate location as requiredalerting appropriate personnel to take necessary actions.

FIG. 13A illustrates ninth embodiment of this invention utilizingvariable speed control of three condenser water pumps operating atpredetermined equal reduced speed or almost equal reduced speed orsimilar reduced speed in lieu of the original/traditional pumpingarrangement as shown in FIG. 4 when chiller(s) is operating. A condenserwater circuit (1300A), In this case, in the condenser water circuit(1300A), Three condenser pumps (1306A, 1307A and 1308A) of the same ornear the same capacity are deployed to transport the produced condenserwater generated by the chiller(s) (1303A,1304A) through the condenserwater circuit (1300A) and reject the heat energy through the coolingtower(s) (1302A, 1305A) to outside atmosphere.

In this case, in the condenser water circuit (1300A), three condenserpumps (1306A, 1307A and 1308A) of the same or near the same capacity aredeployed to transport the produced condenser water through the condenserwater circuit (1300A) if chiller(s) (1303A, 1304A) is operating at themean time in accordance with the current loading.

The three condenser pumps (1306A, 1307A and 1308A) are connected inparallel and operate in predetermined equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously. The threecondenser pumps (1306A, 1307A and 1308A) and corresponding motors arecontrolled by respective variable speed drives (VSD1330A corresponds tocondenser pump 1306A, VSD 1331A corresponds to condenser pump 1307A, VSD1337A corresponds to condenser pump 1308A) and the said drives (1330A,1331A, 1337A) are commanded by a Controller (1333A). The Controller(1333A), monitors the present loading on the water system either bymeasuring the present power consumption of operating chiller(s)' (1303A,1304A) compressor using a power sensor, or the speed of the operatingchiller(s)' (1303A,1304A) compressor using a tachometer or measuringdischarged chilled water temperature and discharged condenser watertemperature leaving the chiller by temperature sensor located inappropriate location in the water circuit or some other means from whichloading can be inferred. Based on that loading signal (1334A), analgorithm calculates the optimum power loading (subject to limits) forthe pumps and sends an output signal (1335A) to the three variable speeddrives (1330A, 1331A, 1337A) operating the three corresponding condenserpumps (1306A, 1307A, 1308A) such that the three condenser pumps (1306A,1307A and 1308A) were incorporated to run at equal reduced speed oralmost equal reduced speed or similar reduced speed simultaneously andoperate at the optimum power percentage (or ratio) (subject to limits)of maximum power draw based on the present percentage (or ratio) ofmaximum loading on the water circuit (1300A).

Again, in the event of variable speed drive(s) or condenser pump(s)failure, an integral bypass switch (1336A, not shown here), can beoperated either manually or automatic, will allow the operative pumps tobe operated at a predetermined speed. At the same time, an alarm signalwill be shown and sent to appropriate location as required alertingappropriate personnel to take necessary actions.

FIG. 14A illustrates tenth embodiment of this invention utilizingvariable speed control of four condenser water pumps operating atpredetermined equal reduced speed or almost equal reduced speed orsimilar reduced speed in lieu of the original/traditional designedpumping arrangement as shown in FIG. 4 when two chillers are operating.In this case, in the condenser water circuit (1400A), Four condenserpumps (1406A, 1407A, 1408A and 1409A) of the same or near the samecapacity are deployed to transport the produced condenser watergenerated by the chillers (1403A and 1404A) through the condenser watercircuit (1400A) and reject the heat energy through the cooling towers(1402A, 1405A, 1439A) to outside atmosphere.

In this case, in the condenser water circuit (1400A), four condenserpumps (1406A, 1407A, 1408A, 1409A) of the same or near the same capacityare deployed to transport the produced condenser water through thecondenser water circuit (1400A) if two chiller (1403A and 1404A) areoperating at the mean time in accordance with the current loading.

The four condenser pumps (1406A, 1407A, 1408A, and 1409A) are connectedin parallel and operate in predetermined equal reduced speed or almostequal reduced speed or similar reduced speed simultaneously. The fourcondenser pumps (1406A, 1407A, 1408A, 1409A) and corresponding motorsare controlled by respective variable speed drives (VSD 1430Acorresponds to condenser pump 1406A, VSD 1431A corresponds to condenserpump 1407A, VSD 1437A corresponds to condenser pump 1408A, VSD 1438Acorresponds to condenser pump 1409A) and the said drives (1430A, 1431A,1437A, 1438A) are commanded by a Controller (1433A). The Controller(1433A), monitors the present loading on the water system either bymeasuring the present power consumption of operating chillers' (1403Aand 1404A) compressor using a power sensor, or the speed of theoperating chillers' (1403A and 1404A) compressor using a tachometer ormeasuring discharged chilled water temperature and discharged condenserwater temperature leaving the chillers by temperature sensor located inappropriate location in the water circuit or some other means from whichloading can be inferred. Based on that loading signal (1434A), analgorithm calculates the optimum power loading (subject to limits) forthe pumps and sends an output signal (1435A) to the four variable speeddrives (1430A, 1431A, 1437A, 1438A) operating the four correspondingcondenser pumps (1406A, 1407A, 1408A, 1409A) such that the fourcondenser pumps (1406A, 1407A, 1408A, 1409A) were incorporated to run atequal reduced speed or almost equal reduced speed or similar reducedspeed simultaneously and operate at the optimum power percentage (orratio) (subject to limits) of maximum power draw based on the presentpercentage (or ratio) of maximum loading on the water circuit (1400A).

As above, in the event of variable speed drive(s) or condenser pump(s)failure, an integral bypass switch (1436A, not shown here), can beoperated either manually or automatic, will allow the operative pumps tobe operated at a predetermined speed. At the same time, an alarm signalwill be shown and sent to appropriate location as required alertingappropriate personnel to take necessary actions.

It will be appreciated that above preferred embodiments, primary chilledwater pumps, secondary chilled water pumps, condenser water pumps,boiler pumps, are shown for illustration, the system can includeadditional units of said pumping arrangements. Additional loads can alsobe connected to the system, and the plurality of operating pump meanscan act responsive to a predetermined target. I.e. a certain flow rate,a certain pressure differential, a desired discharge pressure, etc.

It will be appreciated that the present invention has application in alarge range of industrial fields where pumps are used for pumping fluidsand where the pumping loads are at maximum or vary. The features of theinvention are then able to be used to improve the system efficiencies.

EXAMPLES Example 1

Development of an embodiment of the invention in “primary chilled watercircuit” of a medium size hotel

A medium size hotel with 270 Restrooms is equipped with 3 identicalcapacity 18 KW primary chilled water pumps. Only one primary chilledwater pump is used to circulate the chilled water through the primarychilled water circuit of the HVAC System while the remaining two pumpsare in standby mode. The operating pump is allowed to run uncontrolledat its maximum flow.

Constraints

-   1. Chiller Manufacturer recommends a constant flow of water through    the chiller evaporator (the primary chilled water circuit) of the    HVAC system.-   2. Variable flow in the primary chilled water circuit may cause    instable operation or nuisance shutdown of the chillers; therefore,    chiller manufacturers specify minimum limit for evaporator water    flows.-   3. sufficient flow in the primary chilled water circuit may lead to    freeze up in the evaporator and caused severe damage to the chiller    (ruptured the evaporator tube)-   4. Reduced flow in primary chilled water circuit decreases the    overall heat-transfer effectiveness of the evaporator as the    convective heat transfer coefficient decreases with a reduction in    flow.

Action Taken

1. Three variable frequency drives and one PLC were fitted on theprimary chilled water pumps. The system is coordinated with the buildingmanagement system, enabling easy monitoring of the pump's operation.2. Two of the pumps are operated to run at equal reduced speed about 50%of the maximum speed providing the required constant flow capacity ofthe original systems design requirement. Previously only one pump rancontinuously at maximum speed.

Results

The measures resulted in significant energy savings. The total powerconsumption of the two operating primary chilled water pumps afterfitting of our invention fell by nearly 72 percent compared with atheoretical saving of 75 percent (2×0.5³=0.25) in a perfect condition.Analysis showed that the energy saved was 113,529 kWh per year,resulting in an annual saving of USD 14,600. In addition, an annualmaintenance cost was saved due to the lower pressure imparted to thesystem, reduced excessive vibration and loading on the operating pumpsand respective pipeline.

Example 2

In a pilot test, three variable frequency drives and one PLC were fittedon the primary chilled water pumps. The system is coordinated with thebuilding management system, enabling easy monitoring of the pump'soperation.

Three pumps were run at equal reduced speed of about 34% of the maximumspeed providing the required constant flow capacity of the originalsystems design requirement.

Results

The measures resulted in significant energy savings. The total powerconsumption of the three operating primary chilled water pumps afterincorporation of the described embodiment of the invention fell bynearly 85 percent (3×0.34³=0.12). Analysis showed that the energy savedwas 134,028 kWh per year, resulting in a potential annual saving of USD17,230.

Annual Analysis Results Operating Annual Cost System Flow Pumping EnergyCosts, Saving, Alternatives Consumed US Currency US Currency ConstantPrimary 157,680 kWh  $20,270 NIL Running Two Pumps at 44,150 kWh $5,67014,600 Reducing Speed Running Three Pumps at 23,652 kWh $3,040 17,230Reducing Speed

As the analysis results show, the examples of the inventive system canyield substantial savings when compared with the standard,constant-primary flow design.

Example 3

Development of an embodiment of the invention in “secondary chilledwater circuit”. (under proposed stage)

The said medium size hotel with 270 guestrooms is equipped with two 75KW secondary chilled water pumps. One secondary chilled water pump isused to circulate the water through the secondary chilled water circuitof the HVAC System while the remaining pump is in standby mode. Oneoperating pump is allowed to run at its maximum flow for 20 hours (00:00to 14:00 and 18:00 to 24:00) and at 15% reduced speed of its maximumspeed for 4 hours (14:00 to 18:00) under low loading condition.

Constraints

-   1. Reduced flow in secondary chilled water circuit decreases the    overall heat-transfer effectiveness as the heat transfer coefficient    decreases with a reduction in flow.-   2. the original system has installed two variable speed drives to    the respective pumps and one pump is running at 85% of maximum speed    for a specific period during daytime and has achieving a 10% of    energy saving. The remaining pump is under standby condition.-   3, The embodiment of the invention must provide significant further    saving in order to justify to the user that investment in the system    is worthwhile.

Action Taken

1. Two variable frequency drives and one PLC is fitted on the secondarychilled water pumps. The system is coordinated with the buildingmanagement system, enabling easy control of the pump's operation.2. Two operating chilled water pumps are run at equal reduced speedbetween 43-50% of the maximum speed in accordance with the load,

Results

Analysis showed that a further 60% of energy can be saved in comparisonwith the original designed one secondary chilled pumps riming at 15% ofreducing speed for a specific period (4 hours daily) which can achieved10% of energy saving only. The anticipated power consumption of the twooperating secondary chilled water pumps fell by at least 70% totally.Analysis showed that the estimated energy that can be saved was 459,900kWh per year, resulting in an annual saving of USD 59,120. In addition,an annual maintenance cost can be saved due to the lower pressureimparted to the system, reduced excessive vibration and loading on theoperating pumps and the piping system.

Annual Analysis Results Estimated Operating Annual Cost System FlowPumping Energy Costs, Saving, Alternatives Consumed US Currency USCurrency Constant Secondary 657,000 kWh 84,450 NIL Variable Secondary591,300 kWh 76,000 $8,450 Running Two Pumps at 197,100 kWh 25,330$59,120 Reducing Speed

As the analysis results show, the described embodiment can yieldsubstantial savings when compared with a variable-secondary flow design.

Example 4

Development of an embodiment of the invention in small “single chilledwater circuit”. A manufacturer with 3000 square feet floor area isequipped with two 12.5 KW chilled water pumps. One chilled water pump isused to circulate the chilled water through the single chilled watercircuit of the HVAC while the other pump is in standby mode. Theoperating pump was allowed to run uncontrolled at its maximum flow.

Constraints

-   1. Chiller Manufacturer recommends a constant flow of water through    the chiller evaporator (the single chilled water circuit) of the    HVAC system.-   2. Variable flow in the single chilled water circuit may cause    instable operation or nuisance shutdown of the chiller; therefore,    chiller manufacturers specify minimum limit for evaporator water    flows.-   3. Insufficient flow in the single chilled water circuit may lead to    freeze up in the evaporator and caused severe damage to the chiller,    (ruptured the evaporator tube)-   4. Reduced flow in chilled water circuit decreases the overall    heat-transfer effectiveness of the evaporator as the convective heat    transfer coefficient decreases with a reduction in flow.-   5. Optional market available energy saving methods such as “chilled    water reset”, “colder water, series evaporator”, “colder water,    lower flow”, or simply “variable flow” are neither technologically    viable or would be economically acceptable by the HVAC owner due to    the following reasons:    -   1. High upfront investment    -   2. Long payback period (3 years or above) or unsatisfactory        return    -   3. Involve complicated modification or complexity for control        and operational method.    -   4. The chiller control cannot accommodate for such arrangements.

Action Taken

1. Two variable frequency drives and one PLC were fitted on the singlecircuit chilled water pumps.2. Two single circuit chilled water pumps run at equal reducing speed,about 50% of the maximum speed providing the required constant flowcapacity of the original system design requirement and no standby pumpare provided and be necessary in this situation as bypass and changeovercapability is available in case of emergency/maintenance situations.

Results

The measures resulted in significant energy savings. The powerconsumption of the operating single circuit chilled water pump fell bynearly 73%. Analysis showed that the energy saved was 79,935 kWh peryear, resulting in an annual saving of USD 10,270. In addition, asignificant maintenance cost was saved due to the lower pressureimparted to the system, reduced excessive vibration and loading on theoperating pump and the pipe line.

Example 5

An additional pump is added to the single circuit chilled water systemof Example 4 so that three chilled water pumps are now used, and theyare equipped with three variable frequency drives and one PLC fitted tothe chilled water pumps. The system is equipped with the bypass andchangeover capability, enabling safe operation of the pumping system incase of emergency/maintenance situation. The three pumps are run atsubstantially equal reduced speed, about 34% of the maximum speedproviding the required constant flow capacity of the original systemsdesign requirement.

Results

The estimated total power consumption of the three operating primarychilled water pumps fell by nearly 85%. Analysis showed that theestimate energy saving is 93,075 kWh per year, resulting in an annualsaving of USD 11,960.

Annual Analysis Results Operating Annual Cost System Flow Pumping EnergyCosts, Saving Alternatives Consumed US Currency US Currency ConstantSingle Circuit 109,500 kWh  $14,070 NIL Running Two Pumps at 29,565 kWh$3,800 $10,270 Reducing Speed Running Three Pumps at 16,425 kWh $2,110$11,960 Reducing Speed

As the analysis results show, the described embodiments of the inventivesystem can yield substantial savings when compared with a constantsingle circuit flow design.

Example 6

A central condenser water supply plant is equipped with three 450 KWcentral condenser water pumps. One condenser water pump is used tocirculate sea water through the region's building condenser watercircuits of the HVAC Systems while the remaining two condenser pumps arein standby mode.

Constraint

-   1. The original system designer recommend constant flow    configuration in the central condenser water supply circuit for HVAC    systems' cooling in the region.-   2. Variable flow in the central condenser water supply circuit may    cause instable operation of the chillers in the region especially    the compressor's operation.-   3. Insufficient flow in the central condenser water circuit may lead    to unacceptable temperature rise in the region's condensers and    caused damage to the respective chillers.

Action Taken

Three variable frequency drives and one PLC were fitted on the centralcondenser water pumps. Two operating condenser water pumps run at about50% of the maximum speed providing the required constant flow capacityof the original systems design requirement. Previously one of the pumpswas allowed to run at its maximum flow while the remaining two pumpswere in standby mode.

Results

Estimated energy savings of 70% can be achieved. The power consumptionof the two operating central condenser water pumps after incorporatingthe inventive features is expected to fall by 70%. Analysis showed thatthe estimated energy to be saved is 2,759,400 kWh per year, resulting inan annual saving of USD 354,680. In addition, an annual maintenance costto be saved due to the lower pressure imparted to the system, reducedexcessive vibration and loading on the operating pumps and the pipingsystem.

Example 7

Following the success of Example 6, a second stage improvement wasimplemented. An additional, third pump was added to the centralcondenser water supply circuit thus totaling three condenser water pumpswhich run with three variable frequency drives and one PLC fitted on thecondenser water pumps. The system is equipped with the bypass andchangeover capability, enabling safe operation of the central condenserwater supply system in case of emergency/maintenance situation.

The three condenser pumps are run at substantially equal reduced speed,about 34% of the maximum speed providing the required constant flowcapacity of the original systems design requirement.

Results

The estimated total power consumption of the three operating condenserwater pumps after fitting of the embodiment of the invention fell bynearly 84%. Analysis showed that the estimate energy saving is 3,311,280kWh per year, resulting in an annual saving of USD 425,610.

Projected Annual Energy Consumption Anticipated Estimated OperatingAnnual Cost System Flow Pumping Energy Costs, Saving AlternativesConsumed US Currency US Currency Constant Condenser 3,942,000 kWh$506,680 NIL Running Two Pumps at 1,182,600 kWh $152,000 $354,680Reducing Speed Running Three Pumps at 630,720 kWh $81,070 $425,610Reducing Speed

As the analysis results show, the inventive features can yieldsubstantial savings when compared with a one pump constant-condenserflow design.

Example 8 Swimming Pool Water Re-Circulation Circuit

A residential estate's swimming pool is equipped with two 20 KW poolwater recirculation pumps. One recirculation pump is used to circulatethe pool water though the mechanical filtration and chemical treatmentdevices and then returned to the pool while the other pump is in standbymode. The operating pump was allowed to run uncontrolled at its maximumflow

Constraints

-   1. Disinfection and treatment of swimming pool water is governed by    certain standard and regulations.-   2. The constancy of flow rate is mandated by local standard and    specifications.-   3. The system designer do recommend constant flow configuration in    the pool water recirculation circuit.-   4. A constant quality of pool water which satisfies sanitation    standards, safety and appearance, to avoid spreading bacteria or    contaminant causing diseases.-   5. Variable flow in the pool water recirculation circuit in    accordance with the turbidity of the pool water can not satisfy the    respective standard and regulations requirements fully due to the    following reason;-   6. Insufficient flow in the pool water recirculation circuit may    lead to undesirable excess of chemicals in the pool water and cause    harmful to swimmer's health.

Action Taken

1. Two variable frequency drives and one PLC are fitted on the poolwater recirculation pumps.2. Two water circulating pumps are run at substantially equal reducedspeed, about 50% of the maximum speed, providing the required constantflow capacity of the original system design requirement and no standbypump are provided or deemed necessary in this situation as bypass andchangeover capability is available in case of emergency/maintenancesituation.

Results

The measures have shown significant potential energy savings. Theestimate power consumption of the operating pool water pump afterincorporation of the inventive features fell by nearly 65%. Analysisshowed that the energy to be saved is about 113,880 kWh per year,resulting in an annual saving of USD 14,600. In addition, a significantmaintenance cost can be saved due to the lower pressure imparted to thesystem, reduced excessive vibration and loading on the operating pumpsand the pipeline.

Projected Annual Energy Consumption Anticipated Operating Annual CostSystem Flow Pumping Energy Costs, Saving Alternatives Consumed USCurrency US Currency Constant Primary 175,200 kWh $22,520 NIL RunningTwo Pumps at  61,320 kWh $7,880 $14,640 Reducing Speed

As the analysis results indicate, the inventive system may yieldsubstantial savings when compared with a constant-swimming pool waterrecirculation flow design.

It will be appreciated by persons skilled in the art that numerousvariations and/or modifications may be made to the invention as shown inthe specific embodiments without departing from the spirit or scope ofthe invention as broadly described. The present embodiments are,therefore, to be considered in all respects as illustrative and notrestrictive.

1. An industrial fluid circulating system having one or more fluidcirculation circuits, the system including: a plurality of pump means tocirculate the fluid through each of said circuits, motor means drivingeach pump means, load sensing or detecting means to sense operatingloads on the system and the circuits, and speed control means to varythe speed of said motor means to thereby vary the pumping capacity ofeach pump means in response to the detected load on the system.
 2. Theindustrial fluid circulating system according to claim 1, wherein the oreach said fluid circulation circuits has: one or more fluid circuits;and said pump means comprises two or more pumps of the same capacity orsimilar capacity for each circulation circuit to circulate fluid througheach of said fluid circuits, the pump operation being controlled inaccordance with system load or a predetermined target or manual judgmentof skilled personnel.
 3. The industrial fluid circulating systemaccording to claim 1 or claim 2, wherein said speed control meansincludes a plurality of variable speed drives to operate the associatedpump means.
 4. The industrial fluid circulating system according toclaim 1 or 2, wherein the system loading, or a predetermined target ormanual judgment of skilled personnel, sets an operation speed of each ofthe plurality of pump means, each pump means running at a substantiallysimilar speed, the speed for respective circuits being a predetermined,equally reduced speed, or an almost equal reduced speed or a similarreduced speed, simultaneously.
 5. The industrial fluid circulatingsystem according to claim 1 or 2, wherein said fluid circulationcircuits include a refrigeration system having: one or more chilledwater, condenser water, and boiler water circuits; and said pump meanscomprises two or more pumps for each circuit to circulate water througheach of said water circuits, the pump operation being controlled inaccordance with system load or a predetermined target or manual judgmentof skilled personnel.
 6. The industrial fluid circulating systemaccording to claim 5, wherein cooling system loading is determined bymeasuring the present power consumption of operating chiller(s)compressors) using a power sensor.
 7. The industrial fluid circulatingsystem according to claim 5, wherein cooling system loading isdetermined by measuring the speed of the operating chiller(s)'compressor(s) using a tachometer.
 8. The industrial fluid circulatingsystem according to claim 5, wherein system loading is determined bymeasuring the discharged chilled water/boiler water temperature by atemperature sensor located in an appropriate location in the watercircuit.
 9. The industrial fluid circulating system according to claim5, wherein the cooling system loading or the predetermined target ormanual judgment of the skilled personnel sets operation of selected onesof the plurality of condenser water pumps, chilled water pumps andboiler pumps running at their respective circuit's predetermined equalreduced speed or at almost equal reduced speed or at similar reducedspeed.
 10. The industrial fluid circulating system according to claim 5,wherein the cooling system loading sets operation of selected ones ofthe plurality of condenser water pumps, chilled water pumps and boilerpumps running at their respective circuit's predetermined equal reducedspeed or at almost equal reduced speed or at similar reduced speed andat a power setting that is a fixed ratio of the cooling system currentpower ratio or loading.
 11. The industrial fluid circulating systemaccording claim 1 or 2, wherein each pump means has a power set pointwhich is expressed as:PR-SP_(pd)+C*PR_(load) where PR-SP_(pd) is the power ratio (percent ofmaximum) set point of the respective pump means being controlled,PR_(load) is the current loading/power ratio (percent of maximum) thatis being utilized by a circuit or system, and C is a selected constant,the formula having a low limit to prevent a power ratio set point beingso low as to result in all fluid flow ceasing, and a high limit toensure the power ratio set point would never rise above undesired flowrates and pressure outputs.
 12. The industrial fluid circulating systemaccording to claim 1 or 2, wherein said speed control means includes; avariable-speed drive circuit for powering each of the pump means; anumber of feeding pump means operatively coupled to a number ofreception means with connecting line(s); said motor means driving atleast two of said pump means; means for varying the speed of said motorsmeans; and means for controlling the variable-speed drive circuits inresponse to the present load on the system or act responsive to apredetermined target or manual judgment of skilled personnel so as toregulate operation of the said pump means simultaneously running atequal reduced speed or at almost equal reduced speed or at similarreduced speed.
 13. The industrial fluid circulating system according toclaim 1 or 2, wherein said system includes a variable capacity,compression type, chilled fluid cooling system comprising: a singlecircuit chilled water system including: at least two chilled waterpumps; a variable-speed drive circuit for powering each of the chilledwater pump; a chiller with evaporator operatively coupled to a numbersof cooling loads and a suction line leading back to said chiller; waterpassing through said chiller in a heat exchange relationship and beingcooled; motor means for driving said chilled water pumps; means forvarying the speed of said motor means; means for sensing the temperatureof water leaving said chiller; and means for controlling thevariable-speed drive circuit in response to the present load on a systemcompressor so as, to regulate operation of the said at least two chilledwater pumps running at equal reduced speed or at almost equal reducedspeed or at similar reduced speed simultaneously in response to the loadon the compressor.
 14. The industrial fluid circulating system accordingto claim 1 or 2, wherein the fluid circulation circuits are aprimary-secondary heat absorbing chilled water circuit having at leasttwo primary chilled water pumps, and at least two secondary chilledwater pumps, and said speed control means includes selected ones of; avariable-speed drive circuit for powering each of the primary chilledwater pump; and a variable-speed drive circuit for powering each of thesecondary chilled water pump; the system further having two or morechillers with evaporators being programmed so that the two or morechillers are kept operating or at least one is kept operating andanother remains shutdown and on standby in response to a predeterminedloading condition operatively coupled to a number of cooling loads; anda suction line leading back to said chillers; water passing through saidchillers in a heat exchange relationship and being cooled; said motormeans including motors driving selected ones of said predeterminedoperating primary chilled water pumps and secondary chilled water pumps;means for varying the speed of said operating motors means; means forsensing the temperature of water leaving said operating chiller(s); andmeans for controlling the operating variable-speed drive circuits inresponse to the present load on an operating compressor so as toregulate operation of selected ones of the predetermined plurality ofprimary chilled water pumps and plurality of secondary chilled waterpumps simultaneously running at respective circuit's predetermined equalreduced speed or almost equal reduced speed or similar reduced speed inresponse to the load on the operating compressor.
 15. The industrialfluid circulating system according to claim 1 or 2, wherein one of thefluid circulation circuits is a heat rejection condenser water circuitincluding at least two condenser water pumps; and said speed controlmeans includes; a variable-speed drive circuit for powering each of thecondenser water pump; a chiller with condenser operatively coupled to anumber of cooling towers and a suction line leading back to said chillerwith condenser; water passing through said chillers with condenser in aheat exchange relationship and being heated; said motor means drivingsaid at least two operating condenser water pumps; means for varying thespeed of said motors means; means for sensing the temperature of waterleaving said chillers; and means for controlling the variable-speeddrive circuits in response to the present load on an associatedoperating compressor so as to regulate operation of the at least twooperating condenser water pumps simultaneously running at equal reducedspeed or at almost equal reduced speed or at similar reduced speed inresponse to the loading on the system.
 16. The industrial fluidcirculating system according to claim 13, wherein the chiller includesmeans for regulating the flow of refrigerant gas through the compressor,and the means for determining a present load on the compressor makesthat determination in response to a present state of the gas flowregulating means in the compressor.
 17. The industrial fluid circulatingsystem according to claim 16, wherein the means for determining apresent load on the compressor makes that determination in response to alevel of power applied to the compressor motor or the sensed temperatureof water leaving said chiller.
 18. The industrial fluid circulatingsystem according to claim 16, wherein the means for determining apresent load on the compressor and the means for controlling thevariable speed drive circuit is configured to regulate the variablespeed drive circuit at the predetermined percentage of full powerthereby running selected ones of the plurality of chilled water pumps,condenser water pumps and boiler pumps simultaneously at respectivecircuits' predetermined equal reduced speed or at almost equal reducedspeed or at similar reduced speed to minimize power while system loadingis at maximum or below maximum loading.
 19. The industrial fluidcirculating system according to claim 1 or 2, wherein said plurality ofpump means comprises three or more fluid pumps for each circuitoperating at equal reduced speed or at almost equal reduced speed or atsimilar reduced speed simultaneously.
 20. The industrial fluidcirculating system according to claim 1 or 2, wherein the speed controlmeans for varying the speed of said pump means simultaneously at equalreduced speed or at almost equal reduced speed or at similar reducedspeed acts in response to a predetermined target or the manual judgmentof skilled personnel.
 21. A method of operating an industrial systemhaving one or more water, or other fluid circulation circuits comprisingthe steps of: providing a plurality of pump means to circulate fluidthrough each of said circuits; operating motor means to drive each pumpsmeans, sensing operating loads on the system and the circuits; andvarying the speed of said motor means at respective circuit'spredetermined equal reduced speed or at almost equal reduced speed or atsimilar reduced speed to thereby vary the pumping capacity of each pumpmeans in response to the sensed load on the system; or in response to apredetermined target; or in response to manual judgment of skilledpersonnel.
 22. The method according to claim 21 including the steps ofcirculating fluid through the or each of said fluid circuits with two ormore pumps of the same capacity or similar capacity for each circulationcircuit, and controlling the pump operation in accordance with systemload or a predetermined target or manual judgment of skilled personnel.23. The method according to claim 21 or 22 including the step ofproviding a plurality of variable speed drives to operate the associatedpump means.
 24. The method according to claim 21 or 22 including thesteps of setting an operational speed for each of the plurality of pumpmeans so that each pump means runs at a substantially similar speedwhich is a predetermined, equally reduced speed or an almost equalreduced speed or a similarly reduced speed, simultaneously, for eachrespective circuit in response to the system loading or a predeterminedtarget or manual judgment of skilled personnel.
 25. The method accordingto claim 21 including the steps of providing a refrigeration systemhaving one or more chilled water, condenser water, and boiler watercircuits, circulating water through the or each of said water circuitsusing said pump means comprising two or more pumps for each circuit, andcontrolling the pump operation in accordance with system load or apredetermined target or manual judgment of skilled personnel.
 26. Themethod according to claim 21 or 22 including the steps of determiningcooling system loading by measuring the present power consumption ofoperating chiller(s) compressor(s) using a power sensor.
 27. The methodaccording to claim 21 or 22 including the steps of determining coolingsystem loading by measuring the speed of the operating chiller(s)'compressor(s) using a tachometer.
 28. The method according to claim 21or 22 including the steps determining system loading by measuring thedischarged chilled water/boiler water temperature by a temperaturesensor located in an appropriate location in the water circuit.
 29. Themethod according to claim 25 including the steps of setting operation ofselected ones of the plurality of condenser water pumps, chilled waterpumps and boiler pumps running at their respective circuit'spredetermined equal reduced speed or at almost equal reduced speed or atsimilar reduced speed using the cooling system loading or thepredetermined target or manual judgment of the skilled personnel. 30.The method according to claim 25 including the steps of using thecooling system loading to set operation of selected ones of theplurality of condenser water pumps, chilled water pumps and boiler pumpsrunning at their respective circuit's predetermined equal reduced speedor at almost equal reduced speed or at similar reduced speed and at apower setting that is a fixed ratio of the cooling system current powerratio or loading.
 31. An industrial fluid circulating system having aplurality of fluid circulation circuits comprising: a variable capacity,compression type, chilled fluid cooling system comprising: a singlecircuit chilled water system including: at least two chilled waterpumps; a chiller with evaporator operatively coupled to a numbers ofcooling loads and a suction line leading back to said chiller; waterpassing through said chiller in a heat exchange relationship and beingcooled; motor means for driving said chilled water pumps; avariable-speed drive circuit for powering each of the motor means tovary the speed of the chilled water pumps; means for sensing thetemperature of water leaving said chiller; and means for controlling thevariable-speed drive circuit in response to the present load on a systemcompressor so as to regulate operation of the said at least two chilledwater pumps running at equal reduced speed or at almost equal reducedspeed or at similar reduced speed simultaneously in response to the loadon the compressor.
 32. The industrial fluid circulating system accordingto claim 31 wherein the chiller includes means for regulating the flowof refrigerant gas through the compressor, and the means for determininga present load on the compressor makes that determination in response toa present state of the gas flow regulating means in the compressor. 33.The industrial fluid circulating system according to claim 31 or claim32 wherein the means for determining a present load on the compressormakes that determination in response to a level of power applied to thecompressor motor or the sensed temperature of water leaving saidchiller.
 34. The industrial fluid circulating system according to claim31 or 32, wherein the means for determining a present load on thecompressor and the means for controlling the variable speed drivecircuit is configured to regulate the variable speed drive circuit atthe predetermined percentage of full power thereby running the selectedones of the plurality of chilled water pumps, condenser water pumps andboiler pumps at respective circuits' predetermined equal reduced speedor at almost equal reduced speed or at similar reduced speed to minimizepower while system loading is at maximum or below maximum loading. 35.The industrial fluid circulation system according to claim 1 or 2,wherein the fluid is a liquid.
 36. The method according to claim 21 or22, wherein the fluid is a liquid.
 37. An industrial systemsubstantially as hereinbefore described with reference to theaccompanying drawings.
 38. A method of operating an industrial systemhaving one or more water, or other fluid circulation circuits having thecombination of steps substantially as hereinbefore described withreference to the accompanying drawings and/or the Examples.